You can save Mii characters as QR codes to the virtual SD card, which can then be imported into other emulators or used on real hardware.
The real magic of is the revival of online sharing. citra mii maker portable
Mii Maker is copyrighted system software. Unlike freeware, it cannot be legally distributed. Users must extract the .cia file from their own modified 3DS console (using GodMode9). This high barrier to entry limits the accessibility of a "plug-and-play" portable solution. You can save Mii characters as QR codes
On Android, dragging CIA files is difficult. Use the (a port of the official app): citra mii maker portable